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From: David Brownell <david-b@pacbell.net>
To: Mark Brown <broonie@sirena.org.uk>
Subject: Re: [patch 2.6.28-rc7] regulator: catch some registration errors
Date: Mon, 5 Jan 2009 15:45:24 -0800
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Cc: Liam Girdwood <lrg@slimlogic.co.uk>, lkml <linux-kernel@vger.kernel.org>,
       davej@redhat.com
References: <200812011335.43551.david-b@pacbell.net> <1228340921.6529.80.camel@vega.slimlogic.co.uk> <20081204111206.GA8019@sirena.org.uk>
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On Thursday 04 December 2008, Mark Brown wrote:
> [ Re Liam's comments about those non-existent cpufreq+regulator drivers ]
>
> On the bright side, looking at the situation with the clock API there
> don't seem to be any other substantial offenders here. ?Most of the
> other users are part of the platform code and get to peer inside the
> clocking structure, so if cpufreq were fixed there shouldn't be much
> problem here.

Last time I looked, no cpufreq driver tried to use <linux/clk.h>
calls.  The reason was simple:  the clock framework code sits in
DRAM, so it can't be executed while changing DRAM clocks.

Those bits of cpufreq had to live in on-chip SRAM (there's usually
a few pages of it) and directly update PLL and other clock config
registers ... then wait for things to stabilize before they returned
and the CPU executed from DRAM again.

- Dave
 

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